Device for well casing perforation with an abrasive fluid jet



June 17, 1969 T. PATRON ETAI- 3,450,203

DEVICE FOR WELL-CASING PERFORATION WITH AN ABRASIVE FLUID JET Filed March 9, 1967 FIG. IA

In ventars, Teodor Ion NlCULESCLLEfi-em ANASTASESCU by: Mm 0 4 United States Patent U.S. Cl. 166-55.1 6 Claims ABSTRACT OF THE DISCLOSURE A device for perforating wells by means of an abrasive fluid jet comprising a tubular collar secured to the lower end of the well tubing string. A tubular check valve means having a mating collar mounted at the lower end of the tubing string so that the tubular check valve is supported in the well tubing string, but can he moved through the string in an upward direction. The tubular check valve means are adapted to permit the flow of the fluid downwardly, but are adapted to close when the fluid flow is reversed and the fluid in the well tubing string flows in an upward direction, thereby the Well perforating device can be pumped through the well tubing string to the surface. The device further includes a centering mechanism which is preferably connected to the check valve means. This centering means comprises a tubular member in which there is mounted a piston. The piston is secured to the tubular member by means of an elastic lock ring which is adapted to release the piston when the fluid pressure in the tubular member has reached a predetermined level. At the lower end of the piston at least one pair of opposite blades are pivotally mounted. The pair of opposite blades are caused to project outwardly when the piston is lowered in the tubular member after it has been released by the elastic lock ring means. The blades, after projecting outwardly, cause the entire well perforating device to be centered in the well casing. A plurality of jet nozzles are disposed between the check valve and the well centering mechanism.

The invention refers to a device for perforating the casing and the sand layers in oil and gas wells with a fluid jet containing abrasive particles.

Devices are already known for perforating the casing in oil and gas wells with the aid of an abrasive fluid jet, which is pumped from the surface by means of pumping units through the tubing string and directed upon the casing walls thnough jet nozzles which are resistant to abrasion, disposed in the walls of a perforator, which is the main element of the device.

These known devices have the disadvantage that, when starting the perforating operations, it is necessary to pull the whole tubing string out of the well, to mount the device at the lower end of this tubing string and to introduce them again in the Well hole. After the perforating operation has been completed a pulling out operation for dismounting the device and the reintroducing of the whole string is necessary. In actively flowing wells these operations make the killing of the well necessary, which may result in the clogging of the producing layer and the reduction of the flowing rate of the well.

The perforating device, according to the invention, does away with the above described disadvantages because it is introduced through the tubing and it is supported at the end of the latter in a supporting sleeve screwed into the lower end of the tubing string. The supporting sleeve has at its lower end an inside collar which supports the whole perforating device consisting of fixing and fastening elements, a ball valve, which serves for pumping the device Patented June 17, 1969 out of the tubing string by reversed circulation of the fluid, a mushroom-shaped head member for pulling out the device by means of an overshot device (not illustrated) in emergency cases, as well as an assembly of perforating elements, and finally at the lower end of the device a mechanism for centering the device in the well casing.

One embodiment of the invention is illustrated in the accompanying drawing in which FIGURES 1a and 1b are longitudinal, partial cross-sectional views of the Well perforating device of the invention.

The device, according to the invention, comprises a hollow body 1, provided with groups of preferably four orifices a, disposed diametrically at pre-established levels, in which jet nozzles are screwed in, consisting of a nozzleholder 2, a nozzle 3 and a small plate 4 made of a hard material.

At the lower part of the body 1, a centering device is screwed in, comprising a cylindrical tube 5, which has thick walls at its upper part, defining a passage through its center, a portion of which has a small diameter b and another portion of which has a seat 0 in which there is mounted a hollow mushroom-shaped member 6 provided with preferably four lateral orifices d, which prevent downward passage of the sand. At the lower part of the cylinder 5 has preferably four lateral windows e.

The lower part of the tubular body 5 is closed by screwing in a plug 7. In the cylinder 5 a piston 8 is reciprocally movably mounted as will be described below. Preferably six V-shaped gaskets and distance rings 10 are arranged between the cylinder 5 and piston 8 and are fixed with a threaded ring 11. In the body of the threaded ring 11 there is disposed a groove f in which there is supported an elastic lock ring 12 in a seat g in the cylindrical tubular body 5. The ring 12 is designed to release the piston 8 at a pressure of about 40 atm.

At the lower part of the piston 8 there are pivotally mounted preferably four blades 13, which, when sucked down by the piston 8, are naturally expanded through the windows e while being guided by a part 14 mounted inside the tubular body 5 by means of shearing pins 15. The downstroke of the piston 8 is limited by a stopping ring 16, which is screwed in the tubular body 5, above the windows e.

At its upper part, the body 1 is screwed in a fastening device. This device comprises a piston 17, which is supported by an interior collar h of a sleeve 18, which forms part of the tubing string as it is screwed in at the lower end of the tubing string. The piston 17 is provided with some fabric rubber gaskets 19, fixed by distance rings 20 and fastened by a fixing threaded ring 21 as illustrated in FIG. 111. A check valve 22 having a ball 23 is provided above the threaded ring 21. The ball 23 is mounted in a case 24 for the ball, which lets the fluid flow only toward the bottom of the well. A mushroom-shaped member 25 extends above the check valve 22, by means of which the device can be pulled out with an overshot device (not illustrated) in case of emergency. At surface or ground level a manifold (not illustrated) is provided for controlling the direct and reverse circulation of the fluid to and from the well. A device is mounted directly above the so-called Christmas tree (not illustrated) to catch the perforator, when it is pumped out of the well by means of a reversed circulation.

In order to achieve perforation, the device is introduced from the surface into the tubing string, in the lower end of which the sleeve 18 with the interior collar h is threadably mounted, and which is aided in its descent by a stream of clean oil introduced in the well by direct circulation. 'Ilhe centering and perforating device passes through the interior collar h of the sleeve 18, and the sealing piston 17 is supported on this collar h fixing thereby the device at the lower end of the tubing string, which may be observed by a sudden rise of the pressure at the pumps.

From this moment on the flow of the fluid to the well casing takes place only through the jet nozzles 3. 'Dhe liquid under pressure enters in the centering device through the orifices d of the mushroom 6 and pushes the piston 8 towards the retainer 16 thereby releasing the top lock ring 12, which yields at a pressure of 40 atm.

The four blades 13 slip upon the conical surface of part 14, coming out until they touch the casing and the device is thus centered in the casing of the well.

Thereafter begins the introduction under pressure of the abrasive fluid, the perforating itself being continued during a pre-established time, after which follows a Washing with clean oil.

For pulling the device out of the well the circulation is reversed by the pumps and the manifold on the surface. When the circulation is reversed, the piston 8 of the centering device is pushed upwards until the top lock ring 12 comes back in its seat g and the blades 13 retire inside the device, whereafter, by raising the pressure, the device is pumped toward the surface and recovered.

In case the piston 8 gets stuck so that the blades 13 remain open, at the moment when they arrive in front of the sleeve 18, they force the guiding part 14, shearing the two pins 15. As a result of the downwards displacement of this part 14, the blades can retire into the interior of the device and the part 14 shoulders at the plug 7.

In emergency cases, the device can be pulled out with an overshot (not illustrated), which can be connected to the part 25.

The device, according to the invention has the following advantages: it makes it possible to perforate the oil sand under pressure having oil in the well; and it is easy to handle and reduces the time necessary to perforate a well.

Although our invention has been illustrated and described with reference to the preferred embodiment thereof, we wish to have it understood that it is in no way limited to the details of such embodiment but is capable of numerous modifications within the scope of the appended claims.

We claim:

1. A fluid jet perforating device adapted to be mounted at the lower end of a well tubing string in a well, comprising in combination:

support means operatively mounted at the lower end of said well tubing string;

tubular check valve means, mounted within said support means and being adapted to stop the fluid flow in said well tubing string when the fluid flows in reverse direction therein; centering means operatively connected to said check valve means; fluid jet nozzle means operatively mounted in said fluid jet valve perforating device and being disposed between said check valve means and said centering means;

said centering means being adapted to center the device within a well casing when the downwardly flowing fluid in the well tubing string has reached a predetermined pressure level.

2. A fluid jet perforating device as set forth in claim 1, wherein said support means comprises an inwardly extending collar and said tubular check valve means comprises an outwardly extending collar, the latter being supported by the tubular string.

3. A fluid jet perforating device as set forth in claim 2, wherein said check valve means comprises emergency connecting means adapted to be connected to an overshot cable device mounted on the surface so that the latter may pull out the fluid jet perforating device in case of an emergency.

4. A fluid jet well perforating device as set forth in claim 3, wherein said check valve means comprises an axial passage and valve seat in communication therewith, a ball operatively mounted in said check valve means and said valve seat being adapted to receive said ball when the fluid circulating in the valve tubing string flows in an upward direction towards the surface, whereby said ball is seated on said valve seat means when said fluid flows through said axial passage towards the surface, thereby closing said passage and causing the well perforating device to be pumped through said well tubing string towards the surface.

5. A fluid jet well perforating device as set forth in claim 4, wherein said centering means comprises an axial tubular passage, piston means operatively mounted in said axial tubular passage, plastic lock ring means connecting said piston means to said well casing centering means, at least one pair of blades oppositely and pivotally mounted at the lower end of said piston means, said elastic lock ring means being adapted to release said piston means in said centering means when the fluid pressure in said well tubing string and said fluid jet well perforating device has reached a predetermined level, whereby said piston means descend in said centering means and said pair of opposite blades are caused to project outwardly, thereby centering said fluid jet well perforating device in said Well.

6. A fluid jet well perforating device as set forth in claim 5, including blade guiding means mounted in said centering means and being adapted to guide said blades outwardly of said centering means when said piston means are released by said elastic lock ring means and are made to descend in said centering means, thereby centering said fluid jet well perforating device in the well casing.

Reference-s Cited UNITED STATES PATENTS 2,034,768 3/1936 ONeill 166-55 X 2,327,051 8/ 1943 Lyons et al. 166-222 2,329,157 9/1943 Frack 166-222 2,624,409 1/ 1953 ONeill 16655 3,066,735 12/1962 Zingg 16655 X FOREIGN PATENTS 467,265 8/ 1950 Canada. 152,214 8/1961 U.S.S.R.

DAVID H. BROWN, Primary Examiner.

US. Cl. X.R. 

